Method of and means for roasting zinc blende and the like



G. BALZ 1,815,040

METHOD OF AND MEANS FOR ROASTING ZINC BLENDE AND THE LIKE July 21, 1931,

Filed Oct. 25, 1928 2 Sheets-Sheet 2 Patented July 21, 1931 PATENT ()FFICIEJ GEORG BALZ, OF T'UBINGEN, GERMANY, ASSIGNOR TO BALZ-ERZRflSTUNG- GIEISIEIIJIP- SCHAFT MIT BESGHRANKTER HAFTUNG, OF GLEIWITZ, GERMANY METHOD OF AND MEANS FOR BOASTING ZINC BLENDE AIFD THE LIKE Application filed October 25, 1928, Serial No. 315,059, and in Austria October 31, 1927.

This invention relates to the roasting .of zinc-blende and other ores through the medium of muflie furnacesth'rough which the ore is fed in one direction and air for the'roasting in the opposite direction.

It is usually difficult to carry out the roasting process in a perfectly satlsfactory manner. At the discharge end of the muffle a too rapid cooling of the materials subjected to the last stages of the roasting process is liable to occur owing to the con-.

tact with the admitted air, and further along the muffle dangerously high temperatures are likely to develop which might cause sintering and the formation of zinc ferrltes. In the. case of high roofed mufiies, moreover, the air is inclined to sweep over the materials without coming into intimate contact with the same.

The object of the present invention isto carry out the roasting process in a manner which allows a perfect control of the same in all its stages and which brings about a rapid oxidation of the materials and a consequent shortening of the roastlng process. This object is achieved according to the invention by setting up within the mufile downward currents of'air adapted to penetrate into the moving ore layer. The means for setting up such currents. preferably consist of fans arranged inside the muflle on vertical, revolving shafts. Theshafts are made hollow so as to allow fresh air to be admitted through the shafts directly under the fans.

Fig. 1 of the accompanying drawings represents a vertical, longitudinal section of the furnace, I

Fig. 2, a horizontal section of the same on the line 2-2 of Fig. 1.

Fig. 3, a section on an enlarged scale of one of the propelling and agitating devices, and

Fig. 4, a section on an enlarged scale of' one of the fanning devices.

The furnace comprises a mufiie 1 one end of which receives the materials from a hopper 3 and a vertical delivery plpe WlllCh is adjustable so that the delivery orlfice can be set more or less close'to the sole of the tion towards a gas outlet 1. A silo 6- wherein the materials are collected before they are discharged, is builtover a fire chamber fitted with a grate 9. From said chamber a flue 8 is run underneath and parallel to the muflle so as to supply heat to the latter. The side walls of the mufile are fitted with inspection apertures 5.

For agitating the materials and at the same time feeding them slowly through the muflie, a plurality of vanes 10 are provided which are mounted on vertical shafts 11. The latter pass through the fine 8 and are held in snugly fitting bearing bushings 16 in the walls which confine the flue. Underneath the latter there are thrust bearings 17 whereon the shaftsare supported, as shown in Fig. 3. To each shaft a worm wheel 12 is secured which meshes with a worm 13 secured to a common driving shaft 1 1. The

latter is operated by a motor 15. Alternate shafts rotate in opposite directions, as indicated in Fig. 2, the gears being for this purpose alternately right and left hand.

The vanes are fitted with propelling blades 10a which are set in an oblique position relative to the vanes, the direction of the obliquity being determined by the direction in which the vane moves.

In order to protect the shafts and vanes from being overheated, they are made 1101- low and divided by partitions 20 and 21 respectively (Fig. 2) into two ducts which communicate with each other at the tip of the vane. space below the shaft, while the other com- "municates with a pipe 18 through which air is forced by means of a blower '19. The air from the blower will thus pass up one of the ducts to the tip of the vane and return thence through the other duct to the discharge, and the shafts and vanes will be effectively cooled.

In order to allow the roasting process to be regulated according to requirements through the entire muifle, the latter is fitted One of the ducts opens into the,

immediately above the aperture 23 and forms a closure for the latter. Rotation may be imparted to the shafts through the medium of belt pulleys 29, each shaft being provided with. two pulleys one of which is a driven pulley and the other a driving pulley whereby motion is transmitted to the next shaft. The first shaft receives its motion from a separate motor 15" The belts are crossed so as to cause adjacent shafts to rotate in opposite directions. All the shafts are hollow and connected to a pipe 27 which sup lies fresh air. The diameter of the pipe 2 is reduced after each shaft so that all the fans will operate under similar pressure conditions. The communication of the pipe 27 with each shaft 24 is controlled by means of a valve 26.

The materials are fed slowly through the muffle during the roasting process. which can be watched through the apertures 5. So long as the valves 26 are closed, the fans 28 agitate the air passing through the muffle and maintain continous downward currents which penetrate the materials underneath. f in any part of the muffle signs of excessive heating should be observed, the valves 26 above this part are opened so as to admit fresh, cold air through the respective shafts.24e. Theair will be blown by the fans into intimate contact with the ore, and while the temperature of the latter is thus kept within safe limits, the roasting willbe intensified, and sintering and the formation of zinc ferrites will be prevented.

The materials in the silo 6 may be treated with a blast of hot air from below in order to produce a-slight agglomerationr The general result of the arrangement will be a better utilization of furnace, particularly if the latter is provided with a high muffle, and a corresponding increase in the output.

The arrangement is applicable to furnaces comprising a tier of roasting cham-v bers and also to furnaces having annular or spiral roasting 'soles. The shape of the fans and their mounting may be modified within the scope of the invention.

I claim:

thereof so as to set up whirling air currents over the surface of the ore layer.

2. The combination with a mufile furnace for roasting zinc blende and the like, of a plurality of vertical rotatable shafts mounted in the roof of the mufile, and fans secured to said shafts inside the mufile and adapted to produce air currents the sole of the muifle.

.3. The structure claimed in claim 2 in combination with sand wells mounted on the roof of the mufile and surrounding the shafts, a disc on each shaft, and a flange on said disc extending downwards into the respective well to provide a gas-tight seal.

4:. A structure as claimed in claim 2 wherein the fan shafts are hollow and adapted to admit air into the muffle.

5. The combination with a'mufiie furnace for roasting zinc blende and the like, of a plurality of hollow, vertical shafts mounted in the roof of the muffle, fans secured to said shafts inside the muffle, means for rotating the shafts and fans so as to produce air currents directed towards the sole of the muflie, air supply pipes connected to the hollow shafts, and valves controlling the admission of air through the different shafts into the muffle.

GEORG BALZ.

1. A method of roasting sulphur containing ores in mechanical furnaces with high roofed muflies, consisting in stirring the ore in the mufile, introducing into the mufiie only enough air to carry out the roasting process, and agitating the air in the mufile independently of the mere introduction directed towards 

